The majority of personal care products in the market today are sold as liquid products. While widely used, liquid products have disadvantages in terms of packaging, storage, transportation, and convenience of use.
Liquid personal care products typically are sold in bottles which add significant cost as well as packaging waste, much of which ends up in land-fills. Liquid personal care products also usually comprise a substantial amount of water in the formula which adds significant weight and size translating into greater shipping and storage costs. Liquid personal care products can also be difficult to use in terms of controlling dosage and the delivery of the product.
It is an object of the present invention to provide a non-lathering dissolvable solid personal care product that can be conveniently and quickly dissolved in the palm of the consumer to reconstitute a liquid product for ease of application to hair and/or skin while providing sufficient topical delivery of active agents for topical hair and/or skin applications. It is a further object of the present invention to provide such a product that can be produced in an economical manner via physical aeration followed by drying.
Existing dissolvable personal care films comprise a water-soluble polymeric structurant and active ingredients. However, in order to achieve the requisite rapid dissolution rates needed for consumer convenience, these films are generally on the order of less than 100 microns thickness (typically 50 microns) and, thereby, are generally of too low a basis weight (typically 50-100 grams of solid per square meter) to enable consumer application of a sufficient dosage of active ingredients for entire body or whole head hair application and performance, i.e., beyond lower dosage applications such as hand cleansing and/or the facial applications.
In order to achieve sufficient dosage of raw materials within the palm of the consumer for whole head hair and whole body skin applications, relatively high basis weights are needed which requires objects with a substantial third dimension (thickness) relative to thin films. Moreover, it has also been found that in order for these objects with a substantial third dimension to quickly dissolve in the palm of the consumer to reconstitute a liquid product for ease of application to hair/skin, they not only comprise a water-soluble polymeric structurant in combination with the active ingredients, but also are in the form of a highly porous and predominantly open-celled (vs. closed-celled) solid structure. It is believed that such water-soluble porous solids comprising predominantly open-cells enable rapid water flux inside the structure exposing a multiplicity of additional solid surface area for vastly increased dissolution rates. This is in contrast to water-soluble porous solids comprised of predominantly closed cells whereby the vast majority of the interior cellular surfaces are not rapidly exposed to the water upon wetting with dissolution progressing predominantly via surface erosion and resulting in slower dissolution.
The production of such rapidly dissolvable open-celled porous solid structures via physical aeration typically requires significant surfactancy as a production means to generate the initial wet foam that can then be dried to the porous solid. For cleansing applications, i.e., personal cleansing and hair shampoos, this is not a problem as this surfactancy is also congruent with the desired cleansing product performance (i.e., lathering). However, for non-cleansing applications, i.e., hair conditioning, styling, in-shower body lotions etc., this surfactancy may be problematic as it can adversely affect the deposition of the intended hydrophobic actives to the hair and skin as well as giving un-desirable in-usage signals of lathering/foaming/squeakiness to the consumer that is not congruent with the intended care functions of these products (conditioning, coating, depositing, moisturizing, styling etc.).
It is thus an object of the present invention to discover a means of production of the porous solids via physical aeration (foaming), and also enabling the formation of a predominantly open-celled foam for rapid dissolution, with minimal surfactancy such that the resulting rapidly dissolving porous solid is substantially non-lathering.
Freeze-drying aqueous solutions of water soluble polymeric structurants with other actives is a known method of producing rapidly dispersing or dissolving porous solids with predominantly open cells via sublimation of water from the aqueous mixture leaving behind a skeleton of the dried polymeric structurant. However, freeze-dried porous solids are typically void of plasticizing agents making them rigid and less desirable. Moreover, freeze-drying is an expensive process and less feasible for economical large scale production for personal care applications. Other traditional dissolvable personal care products include porous solids produced by an anhydrous extrusion process and employing volatile blowing agents to produce the cellular structure via high pressure drop induced expansion of the solid. However, this process is limited to anhydrous solid-sourced surfactants and ingredients which are limited in number and make it more difficult to formulate a personal care product with desired characteristics and performance. It would be highly desirable to produce substantially non-lathering and rapid dissolving porous solids with predominantly open-cells via physical aeration (high shear mechanical stirring or gas injection) and subsequent drying as a more commercially viable production method relative to freeze-drying. However, physical aeration essentially results in an air-in-water high internal phase emulsion (a closed cell wet foam) which upon drying can lead to dried closed cell foam morphology wherein the air bubbles are trapped/encased within the dried polymeric film lamellae or generally collapses into a film in the instances where the foam is unstable.
It is therefore an object of the present invention to provide a substantially non-lathering dissolvable open-celled porous solid personal care product that can be conveniently and quickly dissolved in the palm of the consumer to reconstitute a liquid product for ease of application to hair/skin while providing sufficient topical delivery of active agents for whole head hair and whole body skin applications (with similar performance as today's liquid products). It is a further object of the present invention to provide such a product that can be produced by physical aeration followed by subsequent drying. It is an even further object of the present invention to provide such a product with desirable softness and flexibility.